Some baby dinosaurs lost their teeth as they grew up
Limusaurus probably became a vegetarian
If the Tooth Fairy operated during the Jurassic, the dinosaur called Limusaurus would have kept her busy.
Scientists discovered that the pony-sized Limusaurus lost all its teeth as it grew from hatchling to adult, the first known reptile to do so. A Limusaurus hatchling came into the world armed with at least 42 sharp little gnashers, but an adult had only a toothless beak, according to a new study. One explanation for the tooth loss: The beaked adults were vegetarians, their toothy offspring omnivores.
The find is “fascinating,” says Gregory Erickson of Florida State University, who was not involved with the study. Most dinosaurs gained teeth as they got older, but “here we’re seeing it go the other way, where they start off with teeth and just abandon them.”
As an animal that dispensed with all its teeth as it matured, Limusaurus was definitely the weird kid in class. Dinosaurs generally had more teeth as adults than as hatchlings, Erickson says. And they didn’t just add teeth as they grew; many constantly swapped out their teeth for new teeth. Champion tooth-grower Nigersaurus, for example, replaced each tooth as often as every two to four weeks, according to a previous study, and Erickson has found a number of dinosaurs that replaced their teeth every month or two.
When the first Limusaurus skeletons were discovered in China about 15 years ago, paleontologists were confused. Researchers thought at first that they’d found two very similar species, one with teeth and one without, says study author Shuo Wang of China’s Capital Normal University. They named the one with a beak Limusaurus inextricabilis, or inextricable mud lizard, because the little animals had died in mudholes that probably formed from the footsteps of bigger animals, such as giant dinosaurs.
A closer look at the fossils, which date to roughly 160 million years ago, showed they all belonged to just one species. “We couldn’t believe it,” Wang says.